VR (Virtual Reality) display devices generally include an imaging lens and a display screen. Because different users have different pupil distances, there may be differences in the sense of stereoscopic depth perceived by the users, and thus the VR display system cannot adapt to all users. Existing VR display systems (such as VR helmet) mostly use smart multimedia playback terminals (such as smart phones) as a calculation and display unit, installed in the front of the helmet. In the VR helmet, there are two sets of lens assemblies corresponding to the left and right eyes of a user, respectively. Since different users have different pupil distances, if the distance between the lens assemblies is constant (or fixed), some users may find it difficult to get a good experience when wearing the VR helmet.